This multidisciplinary research partnership is designed to improve body structure and function, activity, and participation in individuals who have sustained a stroke. Over 7.7 million people are living with the effects of a stroke and 700,000 people will experience a stroke or recurrence of a stroke annually. The primary concern for patients, regaining walking function, is well founded because walking soon after stroke can predict discharge from the hospital to home and has a significant influence on participation in the community. The research team consists of mechanical engineers, physical therapists, movement scientists, biomechanists, and an exercise physiologist. The team will attempt to merge two independent interventions, fast treadmill training and functional electrical stimulation, to produce an intervention that can markedly improve function in appropriate candidates. The overall goal of the project is to develop a physiologically based intervention to improve functional ambulation in individuals who have sustained a stroke. The Specific Aims are to: 1) develop and test a fast treadmill training and functional electrical stimulation (FastFES) intervention that improves the walking patterns and energy efficiency during treadmill walking in individuals who have sustained a stroke, 2) develop and test a 12-week training protocol using FastFES to improve body structure and function in individuals who have sustained a stroke, and 3) demonstrate the feasibility and potential effects of FastFES training compared to traditional treadmill training on body function, activity, and participation in individuals who have sustained a stroke. A total of 60 stroke survivors will be rigorously studied over the course of this five-year grant. The results from the first 24 subjects will be used to develop and refine the intervention, determine the appropriate timing of the evaluations, and identify the patient characteristics that should be used to stratify patient group assignments when conducting future clinical studies, The last 36 subjects will participate in an experimental protocol that will provide data for the planning of a multi-center randomized clinical trial, including the sample size needed.